1. Field of the Invention
The present invention relates to a mechanical stamping and drawing presses, and, more particularly, to an apparatus for a positive lock for infinite adjustable stroke connection for adjusting the stroke length.
2. Description of the Related Art
In mechanical presses, it is often desirable to adjust or change the stroke length of a reciprocating member, for example the slide, to which a stamping tool is installed. In some prior art tooth adjustment systems, there is a tendency of the system parts to wear after a certain period of operation time. It would be desirable to provide an apparatus or system which may be utilized to quickly, easily and accurately adjust the stroke length of a slide or other parts while ensuring alignment of the stroke connection system. In addition, in some mechanical presses with an indefinite adjustable stroke mechanism, there will be a small amount of slippage from one connection to a second connection on a press with the connections and eccentric on a crankshaft after hundreds of stroke changes. Thus, if one of the eccentric bushings rotates a percentage of degree in relation to the secondary eccentric on the crankshaft during the stroke adjustment process, this will cause the stroke mechanism to be out of adjustment.
The present invention provides an alignment connection for use in a dual eccentric adjustable stroke connection system for use in changing the stroke length of the slide or other member of the mechanical press such as described in U.S. Pat. No. 5,865,070.
An eccentric on a rotatable crankshaft is supplied within an eccentric bushing disposed thereon. A press connection member, such as a connecting rod or link, is attached about the eccentric bushing. During normal operations, there is a relative movement between the eccentric bushing and the connecting member arm to thereby cause reciprocation of the press slide. During stroke adjustment, pressure oil is communicated between the eccentric bushing and the crankshaft eccentric, thereby relieving the press fit or interference fit there between, and causing the eccentric bushing to expand and form a temporary press fit connection with the connecting arm. At this time, the crankshaft may be rotated, along with its eccentric, to thereby change the position of the eccentric within the eccentric bushing. This causes a change of the stroke length. The oil pressure is then relieved thereby causing the eccentric bushing to contract and again form a press fit with the crankshaft eccentric and release the temporary press fit connection between the outside of the eccentric bushing and the connection member arm. After such oil pressure has been reduced, normal press operations may proceed. During normal operations and repeated press operations and stroke adjustments, there can be slippage between the larger eccentric bushing and the connection arm after repeated stroke changes. Thus, if one of the eccentric bushings rotates a percentages of a degree in relation to the secondary eccentric on the crankshaft during the stroke adjustment process, this will cause the slide parallelism from the bottom of the slide to the top of the bolster on the bed to be out of specification. The addition of the positive lock for infinite adjustable stroke and alignment mechanism ensures that during the stroke adjustment process, no movement or slippage will occur and the stroke adjustment will be made uniformly and accurately during each stroke adjustment.
The invention comprises, in one form thereof, a mechanical press having a press connection member, an eccentric bushing disposed within the press connection member, and a second eccentric member disposed within the eccentric bushing. The second eccentric member releasably connectable within the eccentric bushing. A rotatable crankshaft is connected to the second eccentric member. The invention includes a system for connecting the eccentric bushing with the press connection member to prevent rotation there between and permitting rotation of a second eccentric member within the eccentric bushing whereby rotation of the crankshaft, when the system is activated, causes a press stroke adjustment. The invention also includes an alignment connection means that secures the press connection member or multiple press connection members to the eccentric bushings at a predetermined position that ensures the proper positioning of each and every eccentric within the adjustable stroke bushing.
The invention comprises, in another form thereof, a double acting cylinder means for activating the alignment means, such as a U-bar, into and out of the key ways provided for proper alignment of the eccentric bushing and the press connecting members. The alignment means includes a spring to hold the U-bar open so that the U-bar and the eccentric bushing never come in contact and causes a collision when the eccentric bushing is rotating and fixed to the crankshaft.
An advantage of the present invention is that the mechanical presses may now include a positive lock for infinite adjustable stroke alignment mechanism to ensure simple and compact stroke adjustment connections operated by fluid pressure. This is an improvement over prior stock adjustment connections that utilize keys and/or gearing between the crankshaft and the various eccentrics and ensures no slippage or movement of the larger eccentric and connection arms during stroke adjustment operated by fluid pressure.
Another advantage of the present invention is that mechanical presses with infinite adjustable stroke mechanisms will have a small amount of slippage from one connector to the other connector on a press with multiple connection members and their respective eccentric bushings on a crankshaft after hundreds of stroke changes. The present invention will prevent rotational movement of the eccentric bushing in relation to the secondary eccentric on the crankshaft and the bearing cap not to move out of specification, during the time the press stroke is being adjusted.
Another advantage of the present invention is that the alignment mechanism can be used with the simple and compact stroke adjustment connection operated by fluid pressure. The present invention utilizes a connection that is simple in design and vastly reduces the number of parts necessary for a stroke adjustment mechanism and a method to ensure proper alignment.